Sound and ultra-sound generators



R.LEVAVASSEUR Filed June 3, 1966 Aug. 26,1969

souun Ann ULTRA-sown cnnuons United States Patent O 0,092 Int. Cl. B01j 1/12 U.S. Cl. 204--193 8 Claims ABSTRACT OF THE DISCLOSURE A device for producing powerful sonic and ultrasonic waves. Two coaxial bodies of revolution, adjustable to have a common axis, are provided, one body surrounding the other to define therebetween a path for the passage of a gas for producing said waves. The device has an inlet and an outlet, and a chamber in the path with means for reducing `the turbulence of gas admitted through said in- Iet end. An annular slot is provided inV said path, the upstream end of which opens into said chamber and the downstream end of which opens opposite the sharp edge of a whistle-producing chamber. An auxiliary cavity amplifies the waves produced. An outlet conduit is provided in said path and a heat insulated central conduit extends through the device `and has an opening disposed near the said outlet for the wave-producing gas. The said outlet conduit converges in the direction of the axial zone where said central conduit opens. if

The invention relates to devices for producing waves of frequencies within the sonic and ultrasonic range. Such a device comprises two elements of revolution coaxial with each other and which limit between them the following elements, located successively, in the axial direction, as follows: an inlet chamber for Ithe gas under pressure, said chamber being provided with means to suppress or at least to reduce whirling of the gas stream, an annular opening the upstream end of which is in communication with said chamber, a whistle producing cavity the circular edge of which is disposed opposite the downstream end of said slot, an auxiliary cavity for amplifying the sounds produced, and an outlet conduit.

The invention is more especially but not exclusively concerned with devices of this kind for dividing metallic powders into fine particles. v The invention is concerned with a device wherein the medium line of the axial section of the circular opening is slightly inclined (at an angle comprised between 5 and 20, and preferably averaging 10), with respect to the iaxis of revolution of the device.

According to the present invention, the two elements of revolution of the device are mounted in such manner that they may be displaced slightly in the axial direction with respect to each other, preferably by screwing in order to modify the radial thickness of the opening, in particular between 0.05 and 2 millimeters, locking means, such as a lock nut, being provided for stopping said elements in the desired relative axial position, with centering means, such as three screws mounted radially at 120 with respect to each other, between the outer and the inner elements for keeping the axes of said two elements in coincidence.

Another feature of the invention relates to devices of the kind above mentioned for preventing the formation of agglomerates of particles during the thermal decomposition of some gases such as carbonyl nickel or carbonyl iron, in gases and particles. It consists in providing such a device with a heat insulated central conduit fed with such a gas and opening at the downstream end of the device, in giving the annular outlet conduit of this 3,463,716 Patented Aug. 26, 1969 device a shape converging toward the axial zone where said conduit opens, and in constituting the gas under pressure creating `the sonic or ultrasonic waves by a heated gas such as nitrogen at 250 C. A sharp point having an exponential longitudinal section is preferably disposed coaxially with the device opposite the outlet conduit in order `to prevent the creation of stationary waves capable of regrouping the separated particles.

The invention concerns particularly some applications such as the formation, from a gas constituted by carbonyl nickel, of a very divided nickel powder well adapted to the fabrication of microporous diffusion diaphragms.

Preferred embodiments of the invention will be hereinafter described with reference to the appended drawings given merely by way of example and in which:

FIG. 1 is an axial section of a device for producing sonic or ultrasonic waves of great power, according to the invention.

FIG. 2 shows a system for producing a very divided powder including said device, according to the invention.

The device comprises two elements of revolution coaxial with each other. One of said elements 2 is surrounded by the other 1. These two elements limit respectively between them the following spaces of revolution:

A chamber 3 provided with inlet pipes 4 for receiving the gas under pressure intended to create the waves, said chamber being provided with deector members 5 and distributors 6 to prevent whirling of the gas stream,

An annular opening 7, the upstream end of which communicates with chamber 3,

A whistle producing cavity 8, the sharp edge of which is disposed opposite the downstream end of openings 7,

An auxiliary cavity 9 adapted to amplify the sonic or ultrasonic waves produced in cavity 8, and

An outlet conduit 10 through which the gas and the 'amplified waves ow out.

In the constructions used up to this day, elements 1 and 2 were rigid with each other so that the radial dimen sions of opening 7 could not be modified after construction. This is often a drawback because this factor determines the obtainment of resonance and if it is not possible to adjust it, the ranges available for the other parameters (also important, in particular the velocity of the gas) are greatly reduced.

To obviate this drawback, according `to the invention, the general surface of revolution of annular opening 7 is made of frusto-conical shape, and the two elements 1 and 2 are adjustable axially with respect to each other.

The angle of inclination of said surface is comprised between 5 and 20 but it is preferably about 10.

FIG. 1 shows that element 2 comprises at its upstream end a tubular sleeve 11 provided with external threads and screwed in the cooperating threads of a plate 12 rigid with element 1.

The axial displacements of element 2 with respect to element 1 may be ensured by mere rotation of said tubular sleeve 11 in plate 12, said rotation being controlled with a milled knob 13 rigid with said tubular sleeve 11. Due to the frusto-conical shape of opening 7, such axial displacements correspond to variations of the radial thickness of this opening 7, which variations can be determined with a great precision for all the range of possible values for this thickness (preferably between 0.05 and 2 mm.).

A lock nut 14 mounted on sleeve 11 upstream of plate 12 permits of locking said sleeve with respect to said plate (and consequently element 2 with respect to element 1) for every relative position.

Transverse guiding of element 2 in element 1 is completed by a bracing ring 15 located between said elements and by three centering screws 16 mounted in radial threaded housings of element 1 at 120 to one another and bearing on a cylindrical surface of element 2. These screws permit compensation of the free motion (from about 1 to 2 hundredths of a millimeter) necessary for permitting sliding of element 2 in ring l5.

Thus, in order to modify the thickness of opening 7 to take into account, by example, a variation in the pressure of the gas fed at 4 and consequently in its velocity, it suices to unscrew one of screws 16 and lock nut 14 and to turn knob 13 so as to obtain the desired adjustment, then to screw again said lock nut and said screw, which is particularly simple.

Another feature of the invention, independent of that above described but which may be applied to the device above described, relates to the fabrication of a powder of very fine grain size by means of a gas such as carbonyl nickel Ni(CO)4 or carbonyl iron Fe(CO)5, carrying appropriate germs, adapted to be decomposed by a mere heating into another gas and metallic particles which develop about said germs.

Special precautions must be taken, otherwise said particles will form agglo-merates or chains. In order to prevent this, according to the invention, the sonic or ultrasonic Waves of great power are focalized on the formed particles.

For this purpose, the sonic waves created in cavities 8 and 9` are not diffused to the outside but concentrated in a zone 17 located at the downstream end of the device near its axis. This result is obtained by giving conduit 10 a parabolic general shape, said conduit being limited by two coaxial bell-shaped surfaces 18 and 19.

Furthermore, the gas to be thermally decomposed is conveyed to this zone 17 through a central conduit 20 of the device in such manner that this device is used to project said gas.

In order that the thermal decomposition of this gas may take place in zone 17 where the sound vibrations are intensive and not before, this gas is heated by the gas which has served to create the sound waves, this last mentioned gas being for this purpose previously heated and chosen in such manner as to produce no unfavorable chemical reaction on the gas to be decomposed, and conduit 20 is surrounded with a cooling jacket.

Said jacket is constituted by a hollow coil 21 helically wound about conduit 20 inside a coaxial sleeve 22. Through said coil 21 flows, in the upstream-downstream direction, a water stream which is initially cold. This water stream returns from the open downstream end 23 of said coil 20 toward the upstream end on the outside of said coil between conduit 20 and sleeve 22.

In order to prevent all risks of sticking of the metallic particles that are formed on the downstream ends of bellshaped elements 18 and 19, said elements are advantageously made of a plastic material resisting to high temperature such as the polytetrafluoroethylene.

`In order to prevent the formation of sonic or ultrasonic Stationary waves at the output of this device, the existence of which waves would risk to regroup the separated metallic particles, an exponential profile point 24 is disposed coaxially to the device, with its apex directed toward the outlet of said device, at a distance preferably adjustable therefrom.

The collecting of the formed particles is facilitated by surrounding device (1, 2) and point 24 by an envelope 25 communicating at its lower part with a container 26.

In applications of the invention:

The gas to be decomposed was carbonyl nickel (Ni(CO)4) and the gas for producing the sonic and ultrasonic waves was nitrogen heated to a temperature of about 150 to 350 C.

The frequencies of waves created were comprised between 3,000 and 20,000 Hz. and their intensity in zone 17 was higher than 100 decibels.

The means inclination of opening 7 with respect to the axis of device (1, 2) was 10 and its mean radial thickness of about 0.25 mm.

For a device having an outer diameter of about 10 cm., the ow rate of the gas producing the sonic and ultrasonic waves was preferably higher than 25 litres/ minute, by example about 40 or 50 l./min., while the rate of the gas to be decomposed was about from one to some l./min.

The granulation of most of the particles of nickel was comprised between 20 and 50 Angstroms.

In a general manner, while `the above description discloses what are deemed to be practical embodiments of the invention, said invention is not limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the invention as comprehended within the scope of the appended claims.

What I claim is:

1. A device for producing waves of frequencies within the sonic and ultrasonic range which comprises, in combination,

two elements, both in the form of bodies of revolution having a common axis, surrounding each other and limiting between them an annular space having an inlet end and an outlet end,

means in the portion of said annular space adjoining said inlet end for reducing the turbulency of a gas admitted through said inlet end,

the portion of said annular space adjacent to said portion forming an annular slot of general frustoconical shape with an apex angle ranging from 5 to 20,

one of said elements being provided with a Whistle producing annular cavity next to said slot in the direction toward said annular space outlet, the sharp edge of said whistle producing annular cavity being located opposite the outlet of said annular slot, the portion of said annular space adjoining said Whistle producing annular cavity forming an auxiliary cavity for amplifying the waves produced in said cavity,

an outlet conduit between said auxiliary cavity and the outlet end of said annular space, said two elements being adjustable with respect to each other by relative axial displacement, whereby the radial dimensions of said annular slot can be varied,

centering means for causing the axes of said two elements to coincide,

and means for securing said two elements in their desired axial relative position.

2. A device according to claim 1 wherein the radial dimension of said annular slot is adjustable between 0.05 and 2 mm.

3. A device according to claim 1 wherein said securing means are constituted by a lock nut.

4. A device according to claim 1 wherein said centering means are constituted by three centering screws mounted radially at with respect to each other in the outer element, said screws being applied against the inner element of said two elements.

5. A device according to claim 1 further comprising another heat insulated central conduit opening at the downstream end of the device, and wherein said outlet conduit converges in the direction of the axial zone where said other `central conduit opens.

6. A device according to claim 5, further comprising an exponential shaped end part along the axis of the device opposite the output of said central conduit.

7. A device for producing waves of frequencies within the sonic and ultrasonic range which comprises, in combination,

two elements, both in the form of bodies of revolution having a common axis, surrounding each other and limiting between them an annular space having an inlet end and an outlet end,

means in the portion of said annular space adjoining said inlet end for reducing the turbulency of a gas admitted through said inlet end,

the portion of said annular space adjacent to said portion forming an annular slot,

one of said elements being provided with a whistlepro- -ducing annular cavity next to said slot in the direction toward said annular space outlet, the sharp edge of said Whistle producing annular cavity being located opposite the outlet of said annular slot,

the portion of said annular space adjoining said whistle producing annular cavity forming an auxiliary cavity for amplifying the Waves produced in said cavity,

an outlet conduit between said auxiliary cavity and the outlet end of said annular space,

and another heat insulated central conduit opening at the downstream end of the device,

8. A device according to claim 7, further comprising an exponential shaped end part along the axis of the device opposite the output of said central conduit.

References Cited UNITED STATES PATENTS HOWARD S. WILLIAMS, Primary Examiner U.S. Cl. XR.

said outlet conduit converging in the direction of the 15 75H5; 204e-1571$ 241--301, l

axial z one where said other central conduit opens. 

